Suggest to split core from all handlers #72

Hi,

The list of handlers is becoming long.
I suggest an enhancement that handlers will not (necessarily) be part of this core repo.
Instead, anyone can create a repo called cloudworker-proxy-handler-xxx , and you'll maintain a just list of known handlers. This is common practice in many core libraries that I see.
Technically it is possible today without any change to your code, I just suggest that this will become an "official" (i.e. documented) way to contribute handlers.
The benefits are smaller core size, easier maintenance (separation of concerns), and easier contribution.
WDYT?